Venetian type blinds have a series of slats hung on ladder cords which extend from a headrail to a bottomrail. Depending upon the width of the blind, two or more lift cords are provided. Usually, each lift cord is attached at one end to the bottomrail. The lift cords pass through elongated holes in the slats up to and through the headrail. A cord lock is usually provided in the headrail through which the lift cords pass. The cord lock allows the user to maintain the blind in any desired position from fully raised to fully lowered. The slats rest on rungs between the rails of the ladder cords. The blind is in an open position when the rungs are horizontal. To close most venetian blinds one lifts one rail while allowing the other rail to either remain in place or be lowered. Both the lift cords and the ladder cords are typically nonadjustably connected to the bottomrail.
In U.S. Pat. No. 5,573,051, there is shown a venetian type blind having slats that are notched to form slots on their inside edge and outside edge to accommodate the lift cords. The lift cords pass from the bottomrail to the headrail each passing through a slot on the inside edge or outside edge of each slat. At least two cord-type ladders are provided to hold the slats and are aligned such that the rails of the ladders are adjacent the lift cords and outside the slots cut in the slats. The slots are sized so that the lift cords and the ends of the rungs can loosely fit therein. Because lift cords travel within the slots provided in the slats no cord holes are needed in the slats.
It is known to customize venetian type blinds to fit windows of different sizes. Generally, a standard width blind which is closest to, but wider than, the window is selected to be modified. The headrail, bottomrail and slats are trimmed to fit the width of the window. To maintain symmetry, an equal amount is usually trimmed from each end of the slats. Since the length of the blind is adjustable by simply operating the lift cords, the length of the blind sometimes is not modified. Instead, a standard size blind which is nearest to, but longer than, the length of the window is chosen and the extra length is stacked on the bottomrail which rests on the window sill. However, this arrangement can be aesthetically unappealing and compromises the blind's closure when tilted. Equally unappealing is to simply remove the slats because the portion of the ladders which supported the removed slats would still remain. For the best appearance the blind should be nearly the same length as the window when fully extended. Any change in length should include shortening the ladders as well as removing slats.
In venetian type blinds the rails of ladders, which typically are cords but could be tape, and the lift cords can be attached to the bottomrail in different ways. One manner of attaching a ladder tape to a bottomrail is shown in U.S. Pat. No. 2,652,112 to Walker wherein the lift cord passes through small openings in the middle of each slat. The bottomrail has a hole completely through the top and the bottom surfaces. The opening in the top surface of the bottomrail is slightly narrower than the opening in the bottom surface. The lift cord is inserted through the narrower opening and a knot is formed in the end so that it cannot be pulled back through the narrower opening. The rails of the tape ladder encompass the bottomrail. A channel is provided longitudinally along one side of the bottomrail into which a portion of the tape rail can be folded. A pin is then inserted into the longitudinal channel over the tape rail to frictionally hold the tape rail to the longitudinal channel.
Anderson et al. in U.S. Pat. No. 4,177,853 show a manner of connecting the lift cord and a ladder cord to the bottomrail. In Anderson, the bottomrail has a longitudinal channel provided along the upper surface and a hole provided in the lower surface for each lift cord. A plug is provided in each hole. Each lift cord passes through small openings in the center of each slat, through the longitudinal channel and is connected to a plug. The cord rails pass outside of and adjacent to each side of the bottomrail and are then inserted up through the hole in the lower surface. The cord rails are frictionally held in the opening by the plug. Similarly, to Anderson, German Patent Nos. 1 252 878 and 1 509 182 each disclose a manner of attaching a lift cord and ladder cords to a bottomrail wherein a longitudinal channel is provided in the upper surface of the bottomrail and a hole is provided in the lower surface. In each case the lift cord passes through small openings in the middle of each slat, through the longitudinal channel and attaches to the plug. The cord rails pass outside of and adjacent to each side of the bottomrail and are then inserted up through the hole in the lower surface. The plug frictionally retains the cord rails in the hole. In each case the plug is frictionally retained in the hole and/or is held therein because of the attachment to the lift cord.
Theoretically, the bottomrails described in Anderson and the two German patents could be adjusted for the length of the blinds by removing excess slats, removing the plug, cutting off the excess slack in the cord rails, reinserting the ends of the cord rails up through the hole in the underside of the bottomrail, and then reinserting the plug to hold the cord rails in place. However, one problem with such a procedure is that repeated removal and insertion of the plug results in the fit between the hole and the plug becoming looser such that the cord rails may not be securely held in the hole. Another is that it takes a significant amount of time for the novice.
Accordingly, there is a need for venetian blind having a bottomrail that is readily adjustable so that the blind can be easily customized to fit windows of different lengths. Such a blind should overcome the disadvantages in the prior art by eliminating the stack of excess slats on the bottomrail and the excess ladder portions. Such a blind should permit repeated disconnection and reconnection of the lift cords and ladders without loosening or otherwise deteriorating the connections.